Dye mixtures for dye transfer

ABSTRACT

Thermal transfer dye mixtures comprise at least one azo dye with a coupling component of the diaminopyridine series and at least one triazolopyridine, pyridone and/or 1-aminopyrid-2,6-dione dye.

The present invention relates to novel dye mixtures comprising at leastone azo dye of the formula I ##STR1## where R¹, R² and R³ are identicalor different and each is independently of the others alkyl, alkoxyalkyl,alkanoyloxyalkyl, alkoxycarbonyloxyalkyl or alkoxycarbonylalkyl, each ofwhich may have up to 20 carbon atoms and be phenyl-, C₁ -C₄-alkylphenyl-, C₁ -C₄ -alkoxyphenyl-, halophenyl-, benzyloxy-, C₁ -C₄-alkylbenzyloxy-, C₁ -C₄ -alkoxybenzyloxy, halo -benzyloxy-, halogen-,hydroxyl- or cyano-substituted, hydrogen, unsubstituted or C₁ -C₄-alkyl- or C₁ -C₄ -alkoxy-, halogen- or benzyloxy-substituted phenyl,unsubstituted or C₁ -C₄ -alkyl-, C₁ -C₄ -alkoxy-, halogen- orbenzyloxy-substituted cyclohexyl or a radical of the formula

    [--E--O].sub.m --R.sup.5,

where

E is C₂ -C₆ -alkylene,

M is 1, 2, 3, 4, 5 or 6, and

R⁵ is C₁ -C₄ -alkyl or unsubstituted or C₁ -C₄ -alkyl- or C₁ -C₄-alkoxy-substituted phenyl,

R⁴ is C₁ -C₄ -alkyl,

R⁶ is cyano or carbamoyl, and

D is the radical of a diazo component, and at least one dye of theformula II, III and/or IV ##STR2## where L¹ is C₁ -C₂₀ -alkyl, which maybe substituted and may be interrupted by from 1 to 4 oxygen atoms inether function, substituted or unsubstituted phenyl or hydroxyl,

L² is a 5- or 6-membered carbocyclic or heterocyclic radical,

L³ is cyano, carbamoyl, carboxyl or C₁ -C₄ -alkoxycarbonyl,

L⁴ is oxygen or a radical of the formula ##STR3## where Q¹ is in eachcase C₁ -C₈ -alkyl, which may be interrupted by 1 or 2 oxygen atoms inether function,

X is CH or nitrogen,

L⁵ is hydrogen or C₁ -C₄ -alkyl,

L⁶ and L⁷ are identical or different and each is independently of theother hydrogen, substituted or unsubstituted C₁ -C₁₂ -alkyl, C₅ -C₇-cycloalkyl, substituted or unsubstituted phenyl, substituted orunsubstituted pyridyl, substituted or unsubstituted C₁ -C₁₂ -alkanoyl,C₁ -C₁₂ -alkoxycarbonyl, substituted or unsubstituted C₁ -C₁₂-alkylsulfonyl, C₅ -C₇ -cycloalkylsulfonyl, substituted or unsubstitutedphenylsulfonyl, substituted or unsubstituted pyridylsulfonyl,substituted or unsubstituted benzoyl, pyridylcarbonyl orthienylcarbonyl, or together with the nitrogen atom joining themtogether are unsubstituted or C₁ -C₄ -alkyl-substituted succinimido,unsubstituted or C₁ -C₄ -alkyl-substituted phthalimido or a five- orsix-membered saturated heterocyclic radical, which may contain furtherhetero atoms,

Y is cyano or a radical of the formula CO--Q², CO--OQ² or CO--NHQ²,where Q² is hydrogen, C₁ -C₈ -alkyl, which may be substituted and may beinterrupted by 1 or 2 oxygen atoms in ether function, C₅ -C₇-cycloalkyl, phenyl or tolyl,

and also to a process for the thermal transfer thereof.

In the thermal transfer printing process, a transfer sheet, whichcontains a thermally transferable dye in one or more binders with orwithout suitable assistants on a substrate, is heated from the back withan energy source, for example a thermal head or a laser, in the form ofshort heating pulses (duration: fractions of a second), causing the dyeto migrate out of the transfer sheet and diffuse into the surfacecoating of a receiving medium. The essential advantage of this processis that the amount of dye to be transferred, and hence the colorgradation, is readily controlled by controlling the energy to be emittedby the energy source.

In general, color recording involves the use of the three subtractiveprimaries yellow, magenta and cyan (with or without black).

It is known to carry out the thermal transfer printing process withindividual dyes or else with mixtures of dyes. However, it has beenfound that the dyes that are employed still have application defects.

It is an object of the present invention to provide novel dye mixturesin the magenta region that shall be advantageous for thermal transfer.

We have found that this object is achieved by the dye mixtures definedat the beginning.

D can be derived for example from a diazo component of the aniline,phenylazoaniline, aminothiophene, phenylazoaminothiophene,aminothiazole, phenylazoaminothiazole, aminoisothiazole oraminothiadiazole series.

L² can be derived for example from components of the benzene, indole,quinoline, aminonaphthalene, aminothiazole or aminothiophene series.

Emphasis is given to dye mixtures comprising at least one azo dye of theformula I where the radical D is derived for example from a diazocomponent D-NH₂ of the formula ##STR4## where R⁷, R⁸ and R⁹ areidentical or different and each is independently of the others alkyl,alkoxyalkyl, alkoxycarbonylalkyl or alkanoyloxyalkyl, each of which mayhave up to 12 carbon atoms, hydrogen, cyano, halogen, nitro, a radicalof the formula

    [--E--O].sub.m --R.sup.5

where

E, R⁵ and m are each as defined above, or a radical of the formula--CO--OR¹⁷, --CO--NR¹⁷ R¹⁸, --SO₂ --R¹⁷, --SO₂ --OR¹⁷ or SO₂ --NR¹⁷ R¹⁸,where R¹⁷ and R¹⁸ are identical or different and each is independentlyof the other alkyl, alkoxyalkyl, alkoxycarbonylalkyl oralkanoyloxyalkyl, each of which may have up to 12 carbon atoms, hydrogenor a radical of the formula

    [--E--O].sub.m --R.sup.5

where

E, R⁵ and m are each as defined above,

R¹⁰ is hydrogen, chlorine, cyano, C₁ -C₈ -alkyl, C₁ -C₈ -alkoxy, C₁ -C₈-alkylthio, alkoxyalkyl, which may have up to 8 carbon atoms, phenyl,which may be C₁ -C₄ -alkyl-, C₁ -C₄ -alkoxy- or benzyloxy-substituted,benzyl, benzyloxy or a radical of the formula --CO--OR¹⁷ or --CO--NR¹⁷R¹⁸, where R¹⁷ and R¹⁸ are each as defined above,

R¹¹ is hydrogen, cyano, nitro or a radical of the formula --CO--R¹⁷ or--CO--NR¹⁷ R¹⁸, where R¹⁷ and R¹⁸ are each as defined above,

R¹² is cyano, nitro, formyl or a radical of the formula ##STR5## whereR¹⁷ and R¹⁸ are each as defined above,

R¹³ and R¹⁴ are identical or different and each is independently of theother hydrogen, C₁ -C₄ -alkyl, C₁ -C₄ -alkoxy, chlorine, cyano, nitro ora radical of the formula --CO--OR¹⁷ or --CO--NR¹⁷ R¹⁸, where R¹⁷ and R¹⁸are each as defined above,

R¹⁵ is hydrogen, C₁ -C₄ -alkyl or chlorine, and

R¹⁶ is cyano or a radical of the formula --CO--OR¹⁷ or --CO--NR¹⁷ R¹⁸,where R¹⁷ and R¹⁸ are each as defined above.

Emphasis is further given to dye mixtures comprising at least one dye ofthe formula II, III and/or IV where L² is a radical of the formula##STR6## where n is 0 or 1,

Z¹ is hydrogen, C₁ -C₈ -alkyl, which may be interrupted by 1 or 2 oxygenatoms in ether function, methoxy, ethoxy, C₁ -C₄ -alkylsulfonylamino,mono- or di(C₁ -C₄ -alkyl)aminosulfonylamino, or the radical --NHCOZ⁷ or--NHCO₂ Z⁷, where Z⁷ is phenyl, benzyl, tolyl or C₁ -C₈ -alkyl, whichmay be interrupted by one or two oxygen atoms in ether function,

Z² is hydrogen, methyl, methoxy or ethoxy,

Z³ and Z⁴ are identical or different and each is independently of theother hydrogen, C₁ -C₈ -alkyl, which may be substituted and may beinterrupted by one or two oxygen atoms in ether function, C₃ -C₄-alkenyl, C₅ -C₇ -cycloalkyl, phenyl or tolyl, or together with thenitrogen atom joining them together are a five- or six-memberedsaturated heterocyclic radical, which may contain further hetero atoms,

Z⁵ is halogen, and

Z⁶ is hydrogen, halogen, C₁ -C₈ -alkyl, substituted or unsubstitutedphenyl, substituted or unsubstituted benzyl, cyclohexyl, thienyl,hydroxyl or mono(C₁ -C₈ -alkyl)amino, and

L⁵ is as defined above.

Any alkyl, alkylene or alkenyl appearing in the abovementioned formulaecan be not only straight-chain but also branched.

Any substituted alkyl appearing in the above-mentioned formulae may haveas substituents for example, unless otherwise stated, cyano, phenyl,tolyl, C₁ -C₆ -alkanoyloxy, C₁ -C₄ -alkoxycarbonyl, C₁ -C₄-alkoxycarbonyloxy in which the alkoxy group may be substituted byphenyl or C₁ -C₄ -alkoxy.

Any substituted phenyl or pyridyl appearing in the abovementionedformulae may have as substituents for example halogen, C₁ -C₄ -alkyl orC₁ -C₄ -alkoxy.

E is for example ethylene, 1,2- or 1,3-propylene, 1,2-, 1,3-, 1,4- or2,3-butylene, pentamethylene, hexamethylene or 2-methylpentamethylene.

R¹, R², R³, R⁴, R⁵, Z¹, R⁷, R⁸, R⁹, R¹⁰, R¹³, R¹⁴, R¹⁵, R¹⁷, R¹⁸, L¹,L⁵, L⁶, L⁷, Q¹, Q², Z¹, Z³, Z⁴, Z⁶ and Z⁷ are each for example methyl,ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl or tert-butyl.

R¹, R², R³, R⁷, R⁸, R⁹, R¹⁰, R¹⁷, R¹⁸, L¹, L⁶, L⁷, Q¹, Q², Z¹, Z³, Z⁴,Z⁶ and Z⁷ may each also be for example pentyl, isopentyl, neopentyl,tert-pentyl, hexyl, 2-methylpentyl, heptyl, octyl, 2-ethylhexyl orisooctyl.

R¹, R², R³, R⁷, R⁸, R¹⁷, R¹⁸, L¹, L⁶ and L⁷, may each also be forexample nonyl, isononyl, decyl, isodecyl, undecyl or dodecyl.

R¹, R², R³ and L¹ may each also be for example tridecyl, isotridecyl,tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl oreicosyl. (The designations isooctyl, isononyl, isodecyl and isotridecylare trivial names derived from the alcohols obtained by the oxo process(cf. Ullmanns Enzyklopadie der technischen Chemie, 4th edition, volume7, pages 215 to 217, and volume 11, pages 435 and 436).).

R¹, R², R³, R⁷, R⁸, R¹⁷, R¹⁸, Q², L¹, Z¹ and Z⁷ may each also be forexample 2-methoxyethyl, 2-ethoxyethyl, 2-propoxyethyl, 2-butoxyethyl, 2-or 3-methoxypropyl, 2- or 3-ethoxypropyl, 2- or 3-propoxypropyl, 2- or3-butoxypropyl, 2- or 4-methoxybutyl, 2- or 4-ethoxybutyl or 2- or4-butoxybutyl.

R¹⁰, R¹³ and R¹⁴ may each also be for example methoxy, ethoxy, propoxy,isopropoxy, butoxy, isobutoxy or sec-butoxy.

R¹⁰ may also be for example pentyloxy, isopentyloxy, neopentyloxy,hexyloxy, heptyloxy, octyloxy, 2-ethylhexyloxy, methylthio, ethylthio,propylthio, isopropylthio, butylthio, pentylthio, hexylthio, heptylthio,octylthio or 2-ethylhexylthio.

R¹, R², R³, L¹, Q² and Z¹ may each also be for example 3,6-dioxaheptyl,3,6-dioxaoctyl, 4,8-dioxanonyl, 3,7-dioxaoctyl, 3,7-dioxanonyl,4,7-dioxaoctyl, 4,7-dioxanonyl or 4,8-dioxadecyl.

L¹ may also be for example 3,6,9-trioxadecyl, 3,6,9-trioxaundecyl,3,6,9,12-tetraoxatridecyl, 3,6,9,12-tetraoxatetradecyl,2-methoxycarbonylethyl, benzyl, 1- or 2-phenylethyl, 3-benzyloxypropylor 2-, 3- or 4-chlorophenyl.

L³ may be for example methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl,isopropoxycarbonyl, butoxycarbonyl, isobutoxycarbonyl, orsec-butoxycarbonyl.

R¹, R², R³, L¹ and Z⁶ may each also be for example phenyl, 2-, 3- or4-methylphenyl, 2-, 3- or 4-ethylphenyl, 2-,3- or 4-propylphenyl, 2-, 3-or 4-isopropylphenyl, 2-, 3- or 4-butylphenyl, 2,4 -dimethylphenyl 2-,3- or 4-methoxyphenyl, 2-, 3- or 4-ethoxyphenyl, 2-, 3- or4-isobutoxyphenyl or 2,4-dimethoxyphenyl

L⁶ and L⁷ may each also be for example phenyl, 2-, 3- or 4-methylphenyl,2-, 3- or 4-methoxyphenyl, pyridyl, 2-, 3- or 4-methylpyridyl, 2-, 3- or4-methoxypyridyl, formyl, acetyl, propionyl, butyryl, isobutyryl,pentanoyl, hexanoyl, heptanoyl, octanoyl, 2-ethylhexanoyl,methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, isopropoxycarbonyl,butoxycarbonyl, methylsulfonyl, ethylsulfonyl, propylsulfonyl,isopropylsulfonyl, butylsulfonyl, cyclopentylsulfonyl,cyclohexylsulfonyl, cycloheptylsulfonyl, phenylsulfonyl, tolylsulfonyl,pyridylsulfonyl, benzoyl, 2-, 3- or 4-methylbenzoyl, 2-, 3- or4-methoxybenzoyl, thien-2-ylcarbonyl or thien-3-ylcarbonyl.

R¹, R², R³, Q², L⁶, L⁷, Z³ and Z⁴ may each also be for example2-cyanoethyl, 2- or 3-cyanopropyl, 2-acetyloxyethyl, 2- or3-acetyloxypropyl, 2-isobutyryloxyethyl, 2- or 3-isobutyryloxypropyl,2-methoxycarbonylethyl, 2- or 3-methoxycarbonylpropyl,2-ethoxycarbonylethyl, 2- or 3-ethoxycarbohylpropyl,2-methoxycarbonyloxyethyl, 2- or 3-methoxycarbonyloxypropyl,2-ethoxycarbonyloxyethyl, 2- or 3-ethoxycarbonyloxypropyl,2-butoxycarbonyloxyethyl, 2- or 3-butoxycarbonyloxypropyl,2-(2-phenylethoxycarbonyloxy)ethyl, 2- or3-(2-phenylethoxycarbonyloxy)propyl, 2-(2-ethoxyethoxycarbonyloxy)ethylor 2- or 3-(2-ethoxyethoxycarbonyloxy)propyl.

Q², L⁶, L⁷, Z³ and Z⁴ may each also be for example benzyl,2-methylbenzyl, 1- or 2-phenylethyl, cyclopentyl, cyclohexyl,cycloheptyl or 2-, 3- or 4-methylphenyl.

Z¹ is for example methylsulfonylamino, ethylsulfonylamino,propylsulfonylamino, isopropylsulfonylamino, butylsulfonylamino, mono-or dimethylaminosulfonylamino, mono- or diethylaminosulfonylamino, mono-or dipropylaminosulfonylamino, mono- or diisopropylaminosulfonylamino,mono- or dibutylaminosulfonylamino or (N-methyl-N-ethylaminosulfonyl)amino.

Z⁶ may also be for example, like Z⁵ fluorine, chlorine or bromine.

Z⁶ may also be for example benzyl, 2-methylbenzyl, 2,4-dimethylbenzyl,2-methoxybenzyl, 2,4-dimethoxybenzyl, methylamino, ethylamino,propylamino, isopropylamino, butylamino, pentylamino, hexylamino,heptylamino, octylamino or 2-ethylhexylamino.

Z³ and Z⁴ may each also be for example allyl or methallyl.

L⁶ combined with L⁷ or Z³ with Z⁴ to form together with the nitrogenatom joining them together a five- or six-membered saturatedheterocyclic radical, which may have further hetero atoms, can be forexample PG,12 pyrrolidinyl, piperidinyl, morpholinyl, piperazinyl or N-(C₁ -C₄ -alkyl)piperazinyl.

Preferred mixture components are azo dyes of the formula I where R⁴ ismethyl and R¹, R² and R³ are each independently of the others hydrogen,alkyl or alkoxyalkyl, each of which may have up to 15 carbon atoms andmay be phenyl-, C₁ -C₄ -alkylphenyl-, C₁ -C₄ -alkoxyphenyl- orcyano-substituted, or a radical of the formula

    [--(CH.sub.2).sub.3 --O].sub.p [--CH.sub.2 --CH.sub.2 --O].sub.n --R.sup.6,

where

n is 1, 2, 3 or 4,

p is 0 or 1, and

R⁶ is C₁ -C₄ -alkyl or phenyl.

Preferred mixture components further include azo dyes of the formula Iwhere D is derived from a diazo component that conforms to the formulaVa, Vb, Vd or Vf, in which case R⁷, R⁸ and R⁹ are each independently ofthe others alkyl, alkoxyalkyl, alkoxycarbonylalkyl or alkanoyloxyalkyl,each of which may have up to 10 carbon atoms, hydrogen, cyano, halogen,nitro or a radical of the formula --CO--OR¹⁹, --CO--NR¹⁹ R²⁰, --SO₂--R¹⁹, --SO₂ --OR¹⁹ or --SO₂ --NR¹⁹ R²⁰, where R¹⁹ and R²⁰ are eachindependently of the other alkyl, alkoxyalkyl, alkoxycarbonylalkyl oralkanoyloxyalkyl, each of which may have up to 10 carbon atoms, hydrogenor a radical of the formula

    [--CH.sub.2 --CH.sub.2 --O].sub.n --R.sup.5

where

R⁵ and n are each as defined above.

Preferred mixture components further include azo dyes of the formula Iwhere D is derived from a diazo component that conforms to the formulaVc where

R¹⁰ is hydrogen, chlorine, C₁ -C₈ -alkyl, unsubstituted or C₁ -C₄-alkyl- or C₁ -C₄ -alkoxy-substituted phenyl or benzyl,

R¹¹ is cyano or a radical of the formula --CO--OR¹⁹ or --CO--NR¹⁹ R²⁰,where R¹⁹ and R²⁰ are each as defined above, and

R¹² is a radical of the formula ##STR7## where R¹⁹ and R²⁰ are each asdefined above.

Preferred mixture components further include azo dyes of the formula Iwhere D is derived from a diazo component that conforms to the formulaVe where

R¹⁰ is hydrogen, chlorine, C₁ -C₈ -alkyl, unsubstituted or C₁ -C₄-alkyl- or C₁ -C₄ -alkoxy-substituted phenyl or benzyl, and

R¹² is cyano, nitro, formyl or a radical of the formula --CO--OR¹⁹,where R¹⁹ is as defined above

Preferred mixture components further include azo dyes of the formula Iwhere D is derived from a diazo component that conforms to formula Vgwhere

R¹⁰ is C₁ -C₈ -alkyl, C₁ -C₈ -alkoxy, alkoxyalkyl which may have up to 8carbon atoms, unsubstituted or C₁ -C₄ -alkyl- or C₁ -C₄-alkoxy-substituted phenyl, benzyl or benzyloxy and

R¹¹ is cyano, nitro or a radical of the formula --CO--OR¹⁹, where R¹⁹ isas defined above.

Preferred mixture components further include azo dyes of the formula Iwhere D is derived from a diazo component that conforms to the formulaVc where

R¹⁰ is hydrogen, chlorine, C₁ -C₈ -alkyl, C₁ -C₈ -alkoxy, alkoxyalkyl,which may have up to 8 carbon atoms, unsubstituted or C₁ -C₄ -alkyl- orC₁ -C₄ -alkoxy -substituted phenyl or benzyl or a radical of the formula--CO--OR¹⁹, where R¹⁹ is as defined above,

R¹¹ is cyano or the radical of the formula --CO--OR¹⁹, where R¹⁹ is asdefined above, and

R¹² is cyano, nitro, formyl or a radical of the formula --CO--OR¹⁹,where R¹⁹ is as defined above.

Particularly interesting mixture components are azo dyes of the formulaI where D is derived from a diazo component that conforms to the formulaVa, Vb, Vc, Vd, Ve, Vf or Vg.

Particularly interesting mixture components further include azo dyes ofthe formula I where D is derived from a diazo component that conforms tothe formula ##STR8## where R⁷ is as defined above.

Preferred mixture components also include dyes of the formula II or IIIwhere L³ is cyano.

Preferred mixture components further include dyes of the formula II orIII where L² is derived from a component of the benzene, indole,quinoline, aminonaphthalene, aminothiazole or aminothiophene series.

Preferred mixture components further include dyes of the formula II orIII where L¹ is C₁ -C₁₂ -alkyl, which may be substituted by C₁ -C₆-alkanoyloxy, by C₁ -C₈ -alkoxycarbonyl, whose alkyl chain may beinterrupted by 1 or 2 oxygen atoms in ether function, by phenyl or by C₁-C₄ -alkylphenyl and may be interrupted by 1 or 2 oxygen atoms in etherfunction.

Particularly preferred mixture components are dyes of the formula II orIII where L¹ is alkyl, alkoxyalkyl, alkanoyloxyalkyl oralkoxycarbonyloxyalkyl, which may each have up to 12 carbon atoms,unsubstituted or methyl-substituted benzyl or unsubstituted ormethyl-substituted phenyl.

Particularly preferred mixture components further include dyes of theformula II or III where L² is a radical of the abovementioned formulaVIa, VIc, VIl, VIm, VIn or VIo.

Preference for use as mixture components is given to dyes of the formulaIV where L² is a radical of the formula VIa, VIc, VIl , VIm, VIn, VIo orVIp, of which a radical VIc or VIl is particularly suitable.

Particular emphasis for use as mixture components is also given to dyesof the formula IVa ##STR9## where X is CH or nitrogen,

B¹ and B² are each independently of the other hydrogen, C₁ -C₈ -alkyl,phenyl, tolyl, C₁ -C₈ -alkylcarbonyl, C₁ -C₈ -alkylsulfonyl,phenylsulfonyl, tolylsulfonyl, pyridylsulfonyl, benzoyl, methylbenzoyl,pyridyl -carbonyl or thienylcarbonyl,

B³ is hydrogen, methyl, methoxy or the radical --NHCOR¹⁰ or --NHCO₂ R¹⁰,where R¹⁰ is phenyl, benzyl, tolyl or C₁ -C₈ -alkyl, which may beinterrupted by one or two oxygen atoms in ether function,

B⁴ and B⁵ are each independently of the other hydrogen, C₁ -C₈ -alkyl,2-cyanoethyl, benzyl, C₁ -C₄ -alkanoyloxy -C₂ -C₄ -alkyl, C₁ -C₄-alkoxycarbonyl-C₁ -C₄ -alkyl or C₁ -C₄ -alkoxycarbonyloxy-C₂ -C₄ -alkyland

B⁶ is hydrogen or methyl.

Particular emphasis for use as mixture components is also given to dyesof the formula IVb ##STR10## where X is CH or nitrogen, B⁷ is C₁ -C₆-alkyl, phenyl, tolyl, anisidyl, benzyl, cyclohexyl or thienyl and B¹,B², B⁴, B⁵ and B⁶, are each as defined under the formula IVa.

Very particular emphasis is given to dyes of the formula IVa or IVbwhere B¹ and B² are each independently of the other C₁ -C₈-alkylcarbonyl, benzoyl, methylbenzoyl or thienylcarbonyl.

Very particular emphasis is further given to dyes of the formula VIbwhere X is CH.

Emphasis is given to dye mixtures comprising an azo dye of the formula Iand a dye of the formula II.

Emphasis is further given to dye mixtures comprising an azo dye of theformula I and a dye of the formula III.

Emphasis is further given to dye mixtures comprising an azo dye of theformula I and a dye of the formula IV.

Particular emphasis is given to dye mixtures comprising an azo dye ofthe formula I where D is a radical derived from a diazo component of theformula Vc or Vg, in particular Vc, and a dye of the formula II where L²is a radical of the formula VIl.

Particular emphasis is further given to dye mixtures comprising an azodye of the formula I where D is a radical derived from a diazo componentof the formula Vc or Vg, in particular Vc, and a dye of the formula IIIwhere L² is a radical of the formula VIl.

Emphasis is further given to dye mixtures comprising an azo dye of theformula I where D is a radical derived from a diazo component of formulaVc or Vg, in particular Vc, and a dye of the formula IV where L² is aradical of the formula VIl.

The dye mixtures of the invention generally contain from 10 to 90% byweight, preferably from 40 to 80% by weight, in particular from 40 to60% by weight, each percentage being based on the weight of the dyemixture, of one or more azo dyes of the formula I and also from 10 to90% by weight, preferably from 20 to 60% by weight, in particular from40 to 60% by weight, each percentage being based on the weight of thedye mixture, of one or more dyes of the formula II, III and/or IV.

The novel dye mixtures can be obtained in a conventional manner, forexample by mixing the individual dyes in the abovementioned weightratio.

The azo dyes of the formula I are known per se and described for examplein US-A-4 939 118 or can be obtained by the methods mentioned therein.

The dyes of the formula II, III and IV are likewise known and describedfor example in US-A-5 079 365 and the earlier patent applicationPCT/EP/92/00505.

The dye mixtures of the invention are notable for advantageousapplication properties. They show high solubility in the color ribbon(high compatibility with the binder), high stability in the printingink, good transferability, high image stability (i.e. good lightfastness and also good stability to ambient influences, for examplehumidity, temperature or chemicals) and permit flexible coloristicadaptation to the other subtractive primaries resulting in high-qualitycolor spaces.

Of particular noteworthiness is the spectrally uniform decay rate of theindividual components on irradiation, is the dye which has the inferiorlight fastness as an individual dye does not decay preferentially.

The present invention also provides a process for transferring dyes froma transfer to plastic-coated paper by diffusion or sublimation by meansof an energy source, which comprises using a transfer on which there isa dye mixture as defined at the beginning.

The dye transfers required for the process of the invention are preparedas follows. The dye mixtures are incorporated in a suitable organicsolvent or in mixtures of solvents with one or more binders and with orwithout assistants to form a printing ink. It preferably contains thedye mixture in a molecularly dispersed, i.e. dissolved, form. Theprinting ink can then be knife coated onto an inert substrate and airdried. Suitable organic solvents for the dye mixtures are for examplethose in which the solubility of the dye mixtures at 20° C. is greaterthan 1% by weight, preferably greater than 5% by weight.

Examples are ethanol, propanol, isobutanol, tetrahydrofuran, methylenechloride, methyl ethyl ketone, cyclopentanone, cyclohexanone, toluene,chlorobenzene and mixtures thereof.

As binders it is possible to use any resin or polymer material that issoluble in organic solvents and capable of binding the dye mixture tothe inert substrate in such a way that it will not rub off. Preferenceis here given to those binders which, after the air drying of theprinting ink, hold the dye mixture in the form of a clear, transparentfilm in which no visible crystallization of the dye mixture will occur.

Binders of this type are mentioned for example in EP-A-441 282 and inpatent applications cited therein. Other possibilities are saturatedlinear polyesters.

Preferred binders are ethylcellulose, ethylhydroxyethylcellulose,polyvinyl butyrate, polyvinyl acetate, cellulose propionate andsaturated linear polyesters.

The weight ratio of a binder to dye mixture is in general within therange from 1:1 to 10:1.

Suitable assistants are for example release agents as mentioned in saidEP-A-441 282 and patent applications cited therein. It is also possibleto use in particular organic additives which prevent crystallization ofthe transfer dyes in the course of storage or on heating of the colorribbon, for example cholesterol or vanillin.

Suitable inert substrates are described for example in said EP andpatent applications cited therein. The thickness of the substrate is ingeneral from 3 to 30 μm, preferably from 5 to 10 μm.

The dye receptor layer can be basically any thermally stable plasticlayer that possesses affinity for the dyes to be transferred, forexample modified polycarbonates or polyesters. Further details may befound for example in said EP and patent applications cited therein.

The transfer is effected by means of an energy source, for example bymeans of a laser or by means of a thermal head that must be heatable to≧300° C. in order for dye transfer to take place within the time ranget:0<t<15 msec. In the course of transfer, the dye migrates out of thetransfer sheet and diffuses into the surface coating of the receivingmedium.

The dye mixtures of the invention are also advantageous for dyeingsynthetic materials, for example polyesters, polyamides orpolycarbonates. Of particular suitability are textile fabrics made ofpolyester or polyamide or polyester-cotton blend fabrics.

The novel dye mixtures are also advantageous for preparing color filtersas described for example in EP-A-399 473.

Finally, they can also be used with advantage as colorants for preparingtoners for electrophotography.

Embodiments of the invention will now be more particularly described inmore detail by way of example.

EXAMPLES

Table 1 below lists the individual dyes used as mixture components.

                  TABLE 1                                                         ______________________________________                                        Dye                                                                           No.  Structure                                                                ______________________________________                                         1                                                                             ##STR11##                                                                     2                                                                             ##STR12##                                                                     3                                                                            Dye No. 2 in impure form                                                      (Content: about 90%)                                                           4                                                                             ##STR13##                                                                     5                                                                             ##STR14##                                                                     6                                                                             ##STR15##                                                                     7                                                                             ##STR16##                                                                     8                                                                             ##STR17##                                                                     9                                                                             ##STR18##                                                                    10                                                                             ##STR19##                                                                    11                                                                             ##STR20##                                                                    12                                                                             ##STR21##                                                                    13                                                                             ##STR22##                                                                    14                                                                             ##STR23##                                                                    15                                                                            Dye No. 14 in slightly impure form                                            (Content about 98%)                                                           16                                                                            Dye No. 14 in crude form                                                      (Content about 95%)                                                           17                                                                             ##STR24##                                                                    18                                                                             ##STR25##                                                                    19                                                                             ##STR26##                                                                    20                                                                             ##STR27##                                                                    21                                                                             ##STR28##                                                                    22                                                                             ##STR29##                                                                    23                                                                             ##STR30##                                                                    24                                                                             ##STR31##                                                                    25                                                                             ##STR32##                                                                    26                                                                             ##STR33##                                                                    27                                                                             ##STR34##                                                                    28                                                                             ##STR35##                                                                    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Table 2 below lists the light fastness (LF) of the individual dyes 1 to28 and their thermal stability (TS). The value reported here andhereinafter as a measure of the light fastness is the number of hours ofirradiation after which 20% of the dye quantity originally present hadbeen destroyed.

The thermal stability is determined by storing the prints in a dryingcabinet at 70° C. for 1 week. It is assessed on a scale from 1 to 6,where 1 denotes very good and 6 inadequate.

                  TABLE 2                                                         ______________________________________                                        Dye No.         LE      TS                                                    ______________________________________                                         1              300     1                                                      2              40       3+                                                    3              11       2+                                                    4              12      2                                                      5              28      3                                                      6              14      1                                                      7              13      1                                                      8              8       1                                                      9              43       2+                                                   10              136      2+                                                   11              9       2                                                     12              8       4                                                     13              14       2+                                                   14              40       3+                                                   15              45      2                                                     16              31      3                                                     17              77      1                                                     18              7        2+                                                   19              102     1                                                     20              75      1                                                     21              139     1                                                     22              162     1                                                     23                                                                            24              142     2                                                     25              59      1                                                     26              63      3                                                     27              72       2+                                                   28              67      3                                                     ______________________________________                                    

The dye mixtures used hereinafter all contain the dyes in a weight ratioof 1:1.

General Method:

a) 10 g of dye mixture are stirred with or without brief heating to80°-90° C. into 100 g of a 10% strength by weight solution of a binder(Vylon™ 290 from Toyobo) in 4.5:2:2 v/v/v methyl ethylketone/toluene/cyclohexanone.

The printing ink is applied with a 6 μm doctor to a polyester film 6 μmin thickness whose back has been coated with a suitable lubricatinglayer and is blown dry with a hair dryer in the course of 1 minute.Before the color ribbon is used for printing, it subsequently has to airdry for at least 24 hours, since residual solvent can impair theprinting process.

b) The color ribbons are printed in a computer controlled experimentalsetup equipped with a commercial thermal printing head onto Hitachi VY-SVideo Print Paper.

The energy emitted by the thermal printing head is controlled by varyingvoltage with a pulse duration setting of 7 ms and only one pulse beingemitted. The emitted energy is within the range from 0.7 to 2.0 mJ/dot.

Since the degree of coloration is directly proportional to the energysupplied, it is possible to produce a color wedge and analyze itspectroscopically.

The plot of the depth of shade versus the energy supplied per heatingelement is used to determine the Q* value (=energy in mJ for theabsorbance value 1) and the slope m in 1/mJ.

The results obtained are listed below in Table 3, which additionallyshows the light fastness and the thermal stability.

                  TABLE 3                                                         ______________________________________                                        Mixture of                                                                    dyes        LE      TS         Q*   m*                                        ______________________________________                                        17/6        106     1          1.00 2.27                                      17/4        99      1          1.00 2.11                                      17/7        88      1          1.05 1.88                                      17/13       78      1          0.89 2.52                                      17/5        77      1          1.03 1.95                                      17/18       77      1          1.01 2.07                                      17/8        75      1          1.02 1.84                                      20/2        87       2+        1.06 1.94                                      20/6        75      1          1.07 1.75                                      20/16       74      2          1.08 2.02                                      19/6        113     1          1.05 1.94                                      19/5        90      1          1.04 1.86                                      19/15       87       2+        1.02 2.26                                      19/4        80      1          0.94 2.61                                      19/14       74      2                                                         19/9        101      2*                                                       10/6        133     1          1.01 1.98                                      10/4        113     1          1.02 1.92                                      10/5        104     1          1.08 1.94                                      10/11       94      2                                                         10/9        100     2                                                         10/12       89      2                                                         10/8        88      1          1.00 2.09                                      10/7        81      1          1.03 2.08                                      10/13       75      1          0.93 3.16                                      21/6        125     1          1.01 2.10                                      21/9        116      2+                                                       21/4        105     1          0.97 2.18                                      21/3        99      2          1.03 2.07                                      21/14       97       2+        0.99 2.42                                      21/8        83      1          0.98 2.30                                      21/5        78      1          1.01 2.10                                      21/15       77       2+                                                       21/7        72      1          1.03 2.07                                      1/2         185     2          0.95 2.90                                      1/7         187      2+        1.08 2.13                                      1/4         166     2          0.99 2.28                                      1/5         153     2          0.96 2.29                                      1/6         138     1          1.02 2.31                                      1/3         127      2+        1.09 1.98                                      1/8         93      2          0.97 2.36                                      1/9         100      2+        0.88 3.28                                      9/22        78       2+                                                       9/23        73       2+                                                       9/24        85      2                                                         9/25        62      2                                                         9/26        72       2+                                                       9/27        62       2+                                                       9/28        66      2                                                         ______________________________________                                    

We claim:
 1. Dye mixtures comprising at least one azo dye of the formulaI ##STR36## where R¹, R² and R³ are identical or different and each isindependently of the others alkyl, alkoxyalkyl, alkanoyloxyalkyl,alkoxycarbonyloxyalkyl or alkoxycarbonylalkyl, each of which may have upto 20 carbon atoms and be phenyl-, C₁ -C₄ -alkylphenyl-, C₁ -C₄-alkoxyphenyl-, halophenyl-, benzyloxy-, C₁ -C₄ -alkylbenzyloxy-, C₁ -C₄-alkoxybenzyloxy, halobenzyloxy-, halogen-, hydroxyl- orcyano-substituted, hydrogen, unsubstituted or C₁ -C₄ -alkyl- or C₁ -C₄-alkoxy-, halogen- or benzyloxy-substituted cyclohexyl or a radical ofthe formula

    [--E--O].sub.m --R.sup.5,

where E is C₂ -C₆ -alkylene, M is 1, 2, 3, 4, 5 or 6, and R⁵ is C₁ -C₄-alkyl or unsubstituted or C₁ -C₄ -alkyl- or C₁ -C₄ -alkoxy-substitutedphenyl, R⁴ is C₁ -C₄ -alkyl, R⁶ is cyano or carbamoyl, and D is theradical of a diazo component,and at least one dye of the formula II, IIIand/or IV ##STR37## where L¹ is C₁ -C₂₀ -alkyl, which may be substitutedand may be interrupted by from 1 to 4 oxygen atoms in ether function,substituted or unsubstituted phenyl or hydroxyl, L² is a 5- or6-membered carbocyclic or heterocyclic radical, L³ is cyano, carbamoyl,carboxyl or C₁ -C₄ -alkoxy-carbonyl, L⁴ is oxygen or a radical of theformula ##STR38## where Q¹ is in each case C₁ -C₈ -alkyl, which may beinterrupted by 1 or 2 oxygen atoms in ether function, X is CH ornitrogen, L⁵ is hydrogen or C₁ -C₄ -alkyl, L⁶ and L⁷ are identical ordifferent and each is independently of the other hydrogen, substitutedor unsubstituted C₁ -C₁₂ -alkyl, C₅ -C₇ -cycloalkyl, substituted orunsubstituted phenyl, substituted or unsubstituted pyridyl, substitutedor unsubstituted C₁ -C₁₂ -alkanoyl, C₁ -C₁₂ -alkoxycarbonyl, substitutedor unsubstituted C₁ -C₁₂ -alkylsulfonyl, C₅ -C₇ -cycloalkylsulfonyl,substituted or unsubstituted phenylsulfonyl, substituted orunsubstituted pyridylsulfonyl, substituted or unsubstituted benzoyl,pyridylcarbonyl or thienylcarbonyl, or together with the nitrogen atomjoining them together are unsubstituted or C₁ -C₄ -alkyl-substitutedsuccinimido, unsubstituted or C₁ -C₄ -alkyl -substituted phthalimido ora five- or six-membered saturated heterocyclic radical, which maycontain further hetero atoms, Y is cyano or a radical of the formulaCO--Q², CO--OQ² or CO--NHQ², where Q² is hydrogen, C₁ -C⁸ -alkyl, whichmay be substituted and may be interrupted by 1 or 2 oxygen atoms inether function, C₅ -C₇ -cycloalkyl, phenyl or tolyl, the dye mixturecontaining from 10 to 90% by weight of the dye mixture of dye of formulaI and 90 to 10% by weight of the dye mixture of one or dyes of theformulas II, III and/or IV.
 2. Dye mixtures as claimed in claim 1comprising an azo dye of the formula I and a dye of the formula II. 3.Dye mixtures as claimed in claim 1 comprising an azo dye of the formulaI and a dye of the formula III.
 4. Dye mixtures as claimed in claim 1comprising an azo dye of the formula I and a dye of the formula IV. 5.Dye mixtures as claimed in claim 1 comprising from 10 to 90% by weight,based on the weight of the dye mixture, of one or more azo dyes of theformula I and also from 10 to 90% by weight, based on the weight of thedye mixture, of one or more dyes of the formula II, III and/or IV.
 6. Aprocess for transferring dyes from a transfer to plastic-coated paper bydiffusion or sublimation by means of an energy source, which comprisesapplying an energy source to the transfer containing a dye mixture asclaimed in claim 1.